So I'm basically posting this for anyone experiencing similar issues.
I did a fresh install of MB (portable since it and my library is on an external SSD), and only added a couple of lyric source plugins and a few visualizers.
This one didn't seem to work for me, I can open it and view it just fine when I click on MusicBee > View > Start Visualizer - however right clicking it creates a transparent context menu which turns black as soon as I click anywhere else on MB and then it just freezes.
The music will keep playing just fine but I can't do anything until I force close MB.
I tried this method
but at first - and only at first - I got the same error as in this gif
. After that I can add the panel anywhere and I don't see any class errors, however the right click just doesn't work anymore while the visualizer is in the (bottom atm) panel. It only shows if I have it in a dedicated visualizer tab, and as soon as it does show, transparently, anything else I do will crash MB.
I also removed all of my other visualizers in the meanwhile - the Arrange Panels window did freeze multiple times while I was trying it out, and I think removing other visualizers might have fixed this but I'm not 100% certain. It froze differently than the context menu glitch - as that one will cause the program to not respond according to Windows, and the Arrange Panels issue just caused MB to become unresponsive, however Windows felt like everything was fine
Then I randomly tried switching the visualizer in the bottom panel from CSA to some default one, and when I switched back to CSA - the right click was magically working, the properties window would appear, and I could even right click it in the Visualizer tab (however this tab looks weird now since the bottom panel is showing there too, albeit empty)
Also, I thought the Now Playing was mostly hardcoded but the bottom panel now shows there too, with a header unfortunately, but it's there nonetheless.
So, in conclusion, I'm not sure what exactly I did but now it works and hopefully this helps someone with a similar problem